The Hidden Complexity Inside When a mosquito infected with malaria bites a person, we typically think of it as transmitting “malaria.” But the reality is far more complex. That single mosquito bite might be transmitting one parasite strain—or five, or ten distinct genetic clones simultaneously.
Complexity of Infection (COI) is the number of genetically distinct malaria parasite clones present in a single infection. Understanding COI is crucial for:
Transmission intensity assessment — High COI indicates high transmission Drug resistance monitoring — Polyclonal infections complicate resistance detection Vaccine evaluation — Multiple strains can confound efficacy estimates Elimination strategies — Low COI suggests transmission can be interrupted But measuring COI is surprisingly challenging.